Zero altitude in Mission Planner

I hate to bump an old topic, but I’m having a similar issue. Mission Planner/Tower report altitude zero, and the copter performs as though it’s not getting a reading either. i2c Results pi@navio:~ $ i2cdetect -y 1 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- -- -- -- -- -- -- 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 40: 40 -- -- -- -- -- -- -- 48 -- -- -- -- -- -- -- 50: 50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 70: -- -- -- -- -- -- -- 77 pi@navio:~ $

Barometer example:
pi@navio:~/Navio/Python $ python Barometer.py Temperature(C): 34.220994 Pressure(millibar): 1015.299092 Temperature(C): 34.174799 Pressure(millibar): 1015.346996 Temperature(C): 34.160921 Pressure(millibar): 1015.323508 Temperature(C): 34.162731 Pressure(millibar): 1015.339674 Temperature(C): 34.167156 Pressure(millibar): 1015.306615 Temperature(C): 34.175805 Pressure(millibar): 1015.291977 Temperature(C): 34.188879 Pressure(millibar): 1015.340278 Temperature(C): 34.197863 Pressure(millibar): 1015.394725 Temperature(C): 34.198802 Pressure(millibar): 1015.300449 Temperature(C): 34.187605 Pressure(millibar): 1015.318950 Temperature(C): 34.140338 Pressure(millibar): 1015.299965 Temperature(C): 34.087171 Pressure(millibar): 1015.170994 Temperature(C): 34.080064 Pressure(millibar): 1015.166521 Temperature(C): 34.066521 Pressure(millibar): 1015.128487 Temperature(C): 34.053849 Pressure(millibar): 1015.092520 Temperature(C): 34.095417 Pressure(millibar): 1015.049530 Temperature(C): 34.103329 Pressure(millibar): 1015.086583 Temperature(C): 34.127331 Pressure(millibar): 1015.044995 Temperature(C): 34.158306 Pressure(millibar): 1015.036742 Temperature(C): 34.190153 Pressure(millibar): 1015.034501 Temperature(C): 34.220189 Pressure(millibar): 1015.073987 Temperature(C): 34.245801 Pressure(millibar): 1015.050524 Temperature(C): 34.263032 Pressure(millibar): 1015.052241 Temperature(C): 34.278385 Pressure(millibar): 1015.077721 Temperature(C): 34.287570 Pressure(millibar): 1015.061366 Temperature(C): 34.313450 Pressure(millibar): 1015.048417 Temperature(C): 34.328267 Pressure(millibar): 1015.096381 Temperature(C): 34.352068 Pressure(millibar): 1015.091371 Temperature(C): 34.371981 Pressure(millibar): 1015.070214 Temperature(C): 34.387401 Pressure(millibar): 1015.090396 Temperature(C): 34.404833 Pressure(millibar): 1015.148017 Temperature(C): 34.396922 Pressure(millibar): 1015.158986 Temperature(C): 34.364338 Pressure(millibar): 1015.213004 Temperature(C): 34.324915 Pressure(millibar): 1015.215658 Temperature(C): 34.248684 Pressure(millibar): 1015.313231 Temperature(C): 34.164877 Pressure(millibar): 1015.321501 Temperature(C): 34.187404 Pressure(millibar): 1015.331834 Temperature(C): 34.192634 Pressure(millibar): 1015.331855 Temperature(C): 34.203495 Pressure(millibar): 1015.303157 Temperature(C): 34.206311 Pressure(millibar): 1015.339523 Temperature(C): 34.222536 Pressure(millibar): 1015.320562 Temperature(C): 34.253779 Pressure(millibar): 1015.318870 Temperature(C): 34.262965 Pressure(millibar): 1015.339149 Temperature(C): 34.262294 Pressure(millibar): 1015.348944 Temperature(C): 34.277044 Pressure(millibar): 1015.323508 Temperature(C): 34.264708 Pressure(millibar): 1015.363077 ^CTraceback (most recent call last): File "Barometer.py", line 34, in <module> time.sleep(1) KeyboardInterrupt

During that test, I lifted it off the floor by about 6 feet, and set it back down. Navio+, RPi3

I split this into another issue since your barometer is detectable and outputs the values fine.

Do you have GPS connected and do you test outdoors?

I do not have a secondary GPS, no. I have tested outside, yes. 0 to 400+ feet (estimated), the value in MP showed 0.0Ft. Engaging Alt Hold made it continue on its current vertical path. Ex, if the copter was going up when I engaged, the copter would continue. If descending, so would the copter. If I managed to make it hover in stabilize, it may hover. The barometer was covered with open cell foam, and put in the 3D printed case that one of the users posted. Out of the case and foam, the results are the same.

If I get RTK working on my Reach, and use it as my secondary GPS, can/will it use the RTK signal for height as well?

Did you have GPS fix in flight, was the antenna connected?

The antenna was firmly connected, but the HDOP never dropped below 100.0. So no, no fix.

It seems like Mission Planner doesn’t update altitude data if GPS didn’t get a fix. Could you please launch GPS example and observe if you can get a fix.

After attaching a secondary m7 GPS puck, altitude hold worked as soon as it acquired a lock.